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"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

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BRIEF: Do you have any information on SMCO?

I am currently undertaking a degree research project on the toxic effects (mainly haemolytic anemia in rumen animals) of S-methyl-L-cysteine sulphoxide (SMCO) contained in several Brassica species. I was interested to read your internet article on SMCO and I would be delighted if you could send me any further information on SMCO, such as how it causes haemolytic anemia and how its presence in plant material may be measured (assayed).


The rumen is thought to create dimethyl sulfoxide,two pyruvates and two ammonias from two molecules of S-methylcysteine sulfoxide. The hydrogen in the rumen then reacts with the sulfoxide O to form water and dimethyl disulfide. The dimethyl sulfoxide is the oxidant that rips into the blood cell membranes and oxidizes the hemoglobin. See Benevenga, et al. 1989. pp203-228 in Toxicants of Plant Origin, Vol III. CRC Press and Cheeke, pp302-305. Natural Toxicants in Feeds, Forages and Poisonous Plants, 1998. Interstate Publishers, Inc.